diff --git a/target/s390x/cpu_features.c b/target/s390x/cpu_features.c
index e5a3f71492..fa887d9b6f 100644
--- a/target/s390x/cpu_features.c
+++ b/target/s390x/cpu_features.c
@@ -337,8 +337,9 @@ void s390_fill_feat_block(const S390FeatBitmap features, S390FeatType type,
     int bit_nr;
 
     if (type == S390_FEAT_TYPE_STFL && test_bit(S390_FEAT_ZARCH, features)) {
-        /* z/Architecture is always active if around */
-        data[0] |= 0x20;
+        /* Features that are always active */
+        data[0] |= 0x20;  /* z/Architecture */
+        data[17] |= 0x20; /* Configuration-z-architectural-mode */
     }
 
     feat = find_first_bit(features, S390_FEAT_MAX);
diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
index 3a80f1fc49..8c6cc0aaf7 100644
--- a/target/s390x/kvm.c
+++ b/target/s390x/kvm.c
@@ -1757,41 +1757,25 @@ static int sigp_set_architecture(S390CPU *cpu, uint32_t param,
 {
     CPUState *cur_cs;
     S390CPU *cur_cpu;
+    bool all_stopped = true;
 
-    /* due to the BQL, we are the only active cpu */
     CPU_FOREACH(cur_cs) {
         cur_cpu = S390_CPU(cur_cs);
-        if (cur_cpu->env.sigp_order != 0) {
-            return SIGP_CC_BUSY;
+
+        if (cur_cpu == cpu) {
+            continue;
         }
-        cpu_synchronize_state(cur_cs);
-        /* all but the current one have to be stopped */
-        if (cur_cpu != cpu &&
-            s390_cpu_get_state(cur_cpu) != CPU_STATE_STOPPED) {
-            *status_reg &= 0xffffffff00000000ULL;
-            *status_reg |= SIGP_STAT_INCORRECT_STATE;
-            return SIGP_CC_STATUS_STORED;
+        if (s390_cpu_get_state(cur_cpu) != CPU_STATE_STOPPED) {
+            all_stopped = false;
         }
     }
 
-    switch (param & 0xff) {
-    case SIGP_MODE_ESA_S390:
-        /* not supported */
-        return SIGP_CC_NOT_OPERATIONAL;
-    case SIGP_MODE_Z_ARCH_TRANS_ALL_PSW:
-    case SIGP_MODE_Z_ARCH_TRANS_CUR_PSW:
-        CPU_FOREACH(cur_cs) {
-            cur_cpu = S390_CPU(cur_cs);
-            cur_cpu->env.pfault_token = -1UL;
-        }
-        break;
-    default:
-        *status_reg &= 0xffffffff00000000ULL;
-        *status_reg |= SIGP_STAT_INVALID_PARAMETER;
-        return SIGP_CC_STATUS_STORED;
-    }
+    *status_reg &= 0xffffffff00000000ULL;
 
-    return SIGP_CC_ORDER_CODE_ACCEPTED;
+    /* Reject set arch order, with czam we're always in z/Arch mode. */
+    *status_reg |= (all_stopped ? SIGP_STAT_INVALID_PARAMETER :
+                    SIGP_STAT_INCORRECT_STATE);
+    return SIGP_CC_STATUS_STORED;
 }
 
 static int handle_sigp(S390CPU *cpu, struct kvm_run *run, uint8_t ipa1)